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The root cause of the collapse of Baltimore's Francis Scott Key Bridge when hit by container ship Dali has been identified. It was the wrong placement, by a few millimeters, of the label on one wire. As usual, the National Transportation Safety Board has taken their time and done a detailed investigation--summarized in this short video
      https://www.youtube.com/watch?app=desktop&v=bu7PJoxaMZg

tl;dr - the wire was not completely inserted into a terminal block, due to the wire label wrapped over the ferrule. Over time the connection became intermittent and eventually shut off power on the ship...after which it drifted into the bridge. Of course there were additional contributing problems as well.

The YT video comments include some more interesting details.

[Ed. note: For those not inclined to watch the YouTube video, the narrative summary of the video is listed in the spoiler below.]

*SPOILER* (click to show) *SPOILER* (click to hide)

1. The Dali electrical system distributes power and control signals throughout the vessel.
2. The control circuits contain hundreds of terminal blocks that organize thousands of wires.
3. The wires on the Dali were terminated with metal sleeves called ferrules that allowed for easier assembly into the terminal blocks.
4. Each wire was identified with a labeling band.
5. This image shows several terminal blocks on the Dali with wires connected.
6. To assemble a wire into a terminal block, a tool inserted into a side port opens a spring clamp, which allows the wire's ferrule to slide into place.
7. Removing the tool closes the spring clamp, securing the ferrule firmly against the terminal block's internal conductor bar.
8. Labeling bands identify wires and are typically positioned on the wire insulation.
9. However, many labeling bands on the Dali wires were placed partially on the ferrules, which increased the ferrules' overall circumference.
10. As a result, during vessel construction, some of the ferrules could not be fully inserted in the terminal blocks, including the ferrule on wire 1 from Terminal Block 381.
11. On that wire, the labeling band prevented full insertion of the ferrule, so the spring clamp gripped only the ferrule's tip, resulting in an inadequate connection.
12. Due to this unstable connection, over time the ferrule on wire 1 slipped out of the spring clamp to rest atop the spring clamp face, resulting in a precarious electrical connection.
13. When a gap occurred between the ferrule and the spring clamp face, the electrical circuit was interrupted, leading to a blackout on the Dali.

Original Submission